"Soft" tennis courts of the aforesaid type are superior in various respects to courts having asphalt, cement or other "hard" playing surfaces. It is necessary, however, to maintain a proper amount of moisture within the upper layer of particulate material of a soft court. While above-ground sprinklers are commonly used to periodically "water" soft courts, this technique is wasteful of water, reduces court playing time, and is otherwise less than desirable.
In recognition of the foregoing, it has heretofore been proposed to provide underground watering systems for tennis courts of the type in question. One such known system includes bay means formed of water impervious material, a layer of relatively large ballast rocks overlying the bay means, a water permeable membrane or fabric overlying the ballast rocks, and a layer of relatively fine particulate material overlying the fabric and underlying the uppermost layer of particulate material that contains the playing surface of the court. Water is introduced into and conducted from the bay means via a sump or reservoir having water inlet and outlet means controlling the water level in the sump and in the bay means. During normal operation of the system the water level within the bay means is maintained closely adjacent the water permeable fabric overlying the layer of ballast rocks. When the water level is below the fabric, no water passes from the layer of ballast rock to the material thereabove. When the water level is at or above the membrane, water passes upwardly by capillary action through the particulate material overlying the fabric. A disadvantage of the system is that it is wasteful of water. The considerable volume of water constantly maintained within the bay means, within the sizeable spaces between the ballast rock underlying the permeable fabric, serves only as "filler ". In addition to not being substantively used, such water creates a hydraulic pressure head which accelerates escape of water from the bay through any openings that might inadvertently be present in the impervious material of which the bay is formed. Even more importantly, the system does not utilize any significant amount of the rainfall or other precipitation deposited upon the court after it has been placed in operation. Substantially all of the rain water thereafter passing downwardly through the court into the bay means is promptly discharged therefrom and is unavailable for future use in the system.
Another previously proposed system has a plurality of water impervious bays that are spaced considerable distances in a lateral direction from each other and that are of concave, rather than substantially flat, shape. Each bay contains a perforate and centrally located water supply pipe, and a layer of particulate material through which water can migrate by capillary action. A water permeable fabric or membrane overlies the upper surface of the particulate material within the bays, and also overlies the upper surface of the ground intermediate such bays. The water permeable membrane or fabric is in turn overlaid by a plurality of additional layers of particulate material, which include an uppermost layer containing the playing surface of the tennis court, that are also capable of conducting water upwardly by capillary action. In keeping with the first system described above, the aforesaid system also is wasteful of water. The laterally spaced concave bays are capable of containing only limited quantities of water. Once the bays are filled most of any additional water passing thereto, either from the water supply pipes or from rainfall upon the court, will drain from the system through the wide expanses of earth that are present between the bays and that are covered only by the water permeable fabric. The water supply to the upper surface layer of the court will also be quite non-uniform since those areas of the court overlying the spaced bays will receive considerably more water than those areas overlying the earthen spaces between the bays.